This invention relates generally to magnetic data storage systems, more particularly to thin film read/write heads, and most particularly to a write element with an impedance tailored to be able to match the impedance of a shorten connector between a pre-amp chip and the write element, allowing for both higher data transfer rates and higher storage capacities.
Magnetic disk drives are used to store and retrieve data for digital electronic apparatuses such as computers. In FIGS. 1A and 1B, a magnetic disk data storage system 10 includes a sealed enclosure 12, a disk drive motor 14, and a magnetic disk, or media, 16 supported for rotation by a drive spindle S1 of motor 14. Also included are an actuator 18 and an arm 20 attached to an actuator spindle S2 of actuator 18. A suspension 22 is coupled at one end to the arm 20, and at its other end to a read/write head or transducer 24. The transducer 24 typically includes an inductive write element with a sensor read element (which will be described in greater detail with reference to FIG. 2). As the motor 14 rotates the magnetic disk 16, as indicated by the arrow R, an air bearing is formed under the transducer 24 causing it to lift slightly off of the surface of the magnetic disk 16, or, as it is sometimes termed in the art, to xe2x80x9cflyxe2x80x9d above the magnetic disk 16. Data bits can be written to and read from a magnetic xe2x80x9ctrackxe2x80x9d as the magnetic disk 16 rotates. Also, information from various tracks can be read from the magnetic disk 16 as the actuator 18 causes the transducer 24 to pivot in an arc as indicated by the arrows P. The width of a track is sometimes called the xe2x80x9ctrackwidth.xe2x80x9d Narrower trackwidths allow a greater number of tracks to be placed on a magnetic disk 16, thereby increasing its total storage capacity. The design and manufacture of magnetic disk data storage systems is well known to those skilled in the art.
FIG. 2 depicts a magnetic read/write head 24 of the prior art including a read element 26 and a write element 28. Surfaces of the read element 26 and write element 28 also define a portion of an air bearing surface ABS, in a plane 29, which can be aligned to face the surface of the magnetic disk 16 (see FIGS. 1A and 1B). The read element 26 includes a first shield 30, an intermediate layer 32, which functions as a second shield, and a read sensor 34 that is located within a dielectric medium 35 between the first shield 30 and the second shield 32. The most common type of read sensor 34 used in the read/write head 24 is the magnetoresistive (AMR or GMR) sensor which is used to detect magnetic field signals from a magnetic medium through changing resistance in the read sensor.
The write element 28 is typically an inductive write element which includes a first pole 38 and the intermediate layer 32, which functions as a second pole. A second pole pedestal 42 is connected to a second pole tip portion 45 of the second pole. The first pole 38 and the second pole 32 are attached to each other by a backgap portion 40, with these three elements collectively forming a yoke 41 with the second pole pedestal 42. The area around the first pole tip portion 43 and a second pole tip portion 45 near the ABS is sometimes referred to as the yoke tip region 46. A write gap 36 is formed between the first pole 38 and the second pole pedestal 42 in the yoke tip region 46, and is formed from a non-magnetic electrically insulating material. This non-magnetic material can be either integral with or separate from (as shown here) a first insulation layer 47 that lies between the first pole 38 and the second pole 32, and extends from the yoke tip region 46 to the backgap portion 40.
Also included in write element 28 is a conductive coil layer 48, formed of multiple winds 49. The conductive coil 48 is positioned within a coil insulation layer 50 that lies below the first pole 38. The coil insulation layer 50 thereby electrically insulates the coil layer 48 from the first pole 38 and insulates the multiple winds 49 from each other, while the first insulation layer 47 electrically insulates the winds 49 from the second pole 32.
An inductive write head such as that shown in FIG. 2 operates by passing a writing current through the conductive coil layer 48. Because of the magnetic properties of the yoke 41, a magnetic flux can be induced in the first and second poles 38 and 32 by a write current passed through the coil layer 48. The write gap 36 allows the magnetic flux to fringe out from the yoke 41 (thus forming a fringing gap field) and to cross a magnetic recording medium that is placed proximate the ABS.
FIG. 3 shows an alternative magnetic write element 25 of the prior art including two conductive coil layers 60 and 62. The overall structure of magnetic write element 25 is similar to write element 28 and includes a first pole 38, a second pole 32, a backgap 40, a second pole pedestal 42, a write gap 36, and a first insulation layer 47. The primary differences between this prior art write element 25 and write element 28 of FIG. 2 is the additional write gap layer 27 of which the write gap 36 is part, and the arrangement of two stacked coil layers 60 and 62 rather than a single coil layer 48.
In write element 25 the write gap layer 27 may be formed of a non-magnetic electrically insulating material disposed above the first insulation layer 47. A first coil layer 60 is formed of first multiple winds 64 disposed above the write gap layer 27. The first multiple winds 64 are insulated from one another, and covered by, a second insulation layer 65. A second coil layer 62 is formed of second multiple winds 66 disposed above the second insulation layer 65. The second multiple winds are insulated from one another, and covered by, a third insulation layer 67. The first multiple winds 64 and the second multiple winds 66 are both formed of electrically conductive materials. The second insulating layer 65 and the third insulating layer 67 are both formed from non-magnetic electrically insulating materials. The second insulating layer 65 insulates the first coil layer 60 from the first pole 38 and from the second coil layer 62. The third insulating layer 67 insulates the second coil layer 62 from the first pole 38.
The write element 25 with two coil layers 60 and 62 has certain advantages over the write element 28 with one coil layer 48. Stacking multiple coil layers permits write element 25 to be more compact, shortening the distance from the backgap 40 to the second pole pedestal 42, a distance sometimes referred to as the yoke length YL. A shorter yoke length permits a shorter flux rise time, the length of time necessary for the fringing gap field across the write gap 36 to rise to its maximum intensity from its minimum intensity when an electric current is passed through the coil winds. The rate at which data may be written to a magnetic disk 16 increases as the flux rise time decreases. Therefore, a shorter yoke length allows higher data recording rates to be achieved.
Unfortunately, stacking multiple coil layers in a write element can be a disadvantage as well. Multiple coil layers can increase another parameter, sometimes referred to as the stack height SH, the distance between the top surface of the first pole 38 and the top of the second pole 32. The increased topography of the write element created by a larger stack height can make the formation of the first pole 38 more difficult, leading to both decreased performance and lower yields.
FIG. 4 shows a head gimbal assembly (HGA) according to the prior art. The head gimbal assembly includes a base 21 attached to a load beam 23. The load beam 23 includes an arm 20 attached between the base 21 and a suspension 22. The suspension 22 is attached to the arm 20 at a first end and is attached to a read/write head 24 at an opposite end. A pre-amp chip 142 is attached to the base 21. The pre-amp chip 142 is electrically connected to the read/write head 24 by a metallic interconnection 144 such as copper traces or wires. The metallic interconnection 144 carries electrical signals between the pre-amp chip 142 and the read/write head 24. In addition, the pre-amp chip 142 is connected to a controller connector 146 which can electrically connect the pre-amp chip to a controller (not shown). Thus, the pre amp-chip 142 is also configured to pass electric signals to and from the controller.
The pre-amp chip 142 is located on the base 21 to place it close to the read/write head 24. Shortening the distance between the pre-amp chip 142 and the read/write head 24 allows for a higher circuit resonant frequency, in turn allowing for higher data transfer rates. However, it is also necessary to match the impedance of the metallic interconnection 144 with the impedance of the read/write head 24 as failure to do so may degrade the signal. To match the impedance of prior art read/write heads 24, a metallic interconnection 144 of the prior art has had to be sufficiently long, as impedance in a conductor increases as a function of its length. Consequently, this has necessitated placing the pre-amp chip 142 further away from the read/write head 24 than would otherwise be desirable.
Thus, what is desired is a write element with a lower impedance that would allow a pre-amp chip to be located nearer to the write element and preferably on the load beam itself. Further, it is desired that fabrication of such a write element, and a read/write head incorporating the same, be inexpensive, quick, and simple.
The present invention provides a magnetic recording device and method for making the same having a specifically tailored impedance to allow for a pre-amp chip to be located on the load beam nearer to the recording device than previously possible.
In an embodiment of the present invention a recording device for recording data on a magnetic medium comprises a yoke, a write gap layer, two coil layers, and three insulation layers. The yoke, having a characteristic yoke length, comprises a first pole, a second pole, a backgap portion, and a first pole pedestal, each formed of ferromagnetic materials. The first and second poles each have a pole tip portion aligned with one another. Both poles are magnetically connected by way of the backgap portion, located distal their respective pole tip portions. The first pole pedestal is magnetically connected to, and aligned with, the first pole tip portion. Another embodiment is directed towards incorporating into the yoke a second pole pedestal, also formed of a ferromagnetic material, and situated between the write gap layer and the second pole.
The yoke forms a discontinuous ring with a single gap. Within the interior space defined by the yoke are a write gap layer, two coil layers, and three insulation layers. The write gap layer extends from the write gap region, the space between the first pole pedestal and the second pole tip portion, to the distal end of the second pole, and separates the turns of the first coil layer from the turns of the second coil layer. A first pole insulation layer insulates the first pole from the turns of the first coil layer, and a first coil insulation layer disposed between the turns of the first coil layer insulates those turns from one another. A second coil insulation layer insulates the turns of the second coil layer from each other and from the second pole. The write gap layer and each of the insulation layers may be formed of suitable non-magnetic and electrically insulating materials, while the turns of the two coil layers may be formed of electrically conductive materials. At a minimum, each coil layer has at least one turn.
This structure is advantageous because it allows for a shorter yoke length that reduces the device""s flux rise time, thus, allowing for higher data recording rates. The placement of the write gap layer is also advantageous in this design because it limits the height of the first coil layer, thereby reducing the overall stack height of the device. Reducing the stack height facilitates the formation of the second pole.
Another embodiment of the present invention is a data transfer device for exchanging data with a magnetic medium comprising a load beam to which a recording device and a pre-amp chip are attached. The recording device is configured according to the embodiments previously described. The pre-amp chip is electrically connected to the recording device, and is connectable to a controller. The pre-amp chip is intended to pass electrical signals to and from both the controller and the recording device. Yet another embodiment is directed to locating the pre-amp chip at a sufficient distance from the recording device such that the impedance of the recording device and the impedance of a connector between the recording device and the pre-amp chip are substantially equal. Minimizing the impedance mismatch between the connector and the recording device while locating the pre-amp chip closer to the recording device is advantageous for decreasing the current rise time and the flux rise time, allowing for higher data transfer rates.
Still other embodiments include a read element, also connected to the pre-amp chip. Such a read element may include two shields and a read sensor, where the read sensor is disposed between a first shield and the first pole of the recording device configured to act as a second shield. Yet other embodiments additionally include a medium support and a read/write head support system. The medium support may further include a spindle on which the magnetic medium can be supported, and a medium motor capable of rotating the magnetic medium around the axis of the spindle. The read/write head support system further includes the load beam and pre-amp chip, and is intended to suspend the read/write head proximate to the magnetic medium.
In yet another embodiment of the present invention, a method for forming a recording device includes providing a first pole having a pole tip portion. The first pole is substantially planarized prior to forming a first pole pedestal above and magnetically connected to the first pole at its pole tip portion. A backgap portion is formed above and magnetically connected to the first pole distal to its pole tip portion. A first pole insulation material is deposited over the first pole pedestal, first pole, and backgap portion and a first pre-coil layer is formed above the first pole insulation layer. A first coil insulation layer is deposited over the first pre-coil layer and then substantially planarized to expose the first pole pedestal, first pre-coil layer, and backgap portion. A write gap layer is formed over the exposed first pole pedestal and first coil layer, and a second coil layer is formed above the write gap layer. A second coil insulation layer is formed over the second coil layer, and a second pole is formed over the write gap material and second coil insulation layer, and also over the backgap portion with which it is magnetically connected.
Further embodiments are directed to forming a second pole pedestal within the recording device, forming a read element connected to the recording device, attaching the recording device and the read element to a load beam, and attaching a pre-amp chip to the load beam, to the recording device, and to the read element. Still other embodiments include incorporating the recording device and read element within a read/write head, combining the read/write head with a suspension system, and providing a support system for supporting the magnetic medium proximate to the read/write head.
These and other advantages of the present invention will become apparent to those skilled in the art upon a reading of the following descriptions of the invention and upon studying the several figures of the drawings.